Question Cant use all 4 mobo DIMM slots at same time - but All slots work and all ram works

Aug 30, 2019
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I have recently upgraded to an Intel I7 9900k and Asus strix Z390-E Motherboard. Before describing the issue i must say that i also had TWO Asus strix Z390-F Motherboards with the same issue - which I returned as I assumed were defective. This is now my third motherboard in a row with the same issue. This can't be a hardware problem right?!

The issue I'm having is Ram related. All 4 DIMMS are working correctly as I have tested them one by one on this new Asus strix Z390-E motherboard and on my old Strix x399 Mobo and they all work correctly (I also ran mem test with no detected issues).

The Problem is I can only use 3 DIMM Mobo slots at the same time - if I use all 4 the motherboard refuses to post and just lights up a DRAM LED and turns itself off and on in a loop.

I have tested all slots individually and all the slots are working correctly. I just cant use all 4 of them at the same Time! Can use a max of 3 slots.

Any help would be great! I realy dont want to have to replace a third motherboard and go though all the hassle. And i dont think it would solve the problem either...

Things i have tried (in no specific order):
  1. Testing each DIMM individually (All work correctly)
  2. Testing all DIMM Slots on the motherboard individually (All work correctly so long as i dont use all 4 at the same time!)
  3. Re-seating the CPU cooler
4) replacing the motherboard
I had the same issue on both of my Asus strix Z390-F Mobos and on my Asus strix Z390-E (The one i currently have)

5) Clearing CMOS

6) (RECOMMENDEDMY ASUS SUPPORT) -> go into the BIOS > Advanced Menu > APM Configuration, from here set the ERP Ready to Enabled S4 + S5 or Enabled S5 and set the Restore AC Power Loss to Last State and test the motherboard again.

7) Enabling XMP

8) Updating BIOS

9) Using 2 x hyper-X sticks and 2 x G.Skill sticks (Same issue)


Specs:
I9 9900k
Asus strix Z390-E
32GB DDR4 G.SKILL Trident Z (2 sets of 2 x 8GB DIMMS)
GTX 1080TI (x 2 )
NZXT Kraken x52
1000W PSU
Samsung 1TB 970 Evo
 
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well your x390 will need 4 same sticks (same timings) u cant run one set of timing on one channel, and 2nd one the other

tho its not impossible to do so
try first with increasing memory controller/ram voltage

anyway, please write part numbers for your ram
 
Yep, it's pretty normal to have to up the memory controller or RAM voltage when filling all slots, because that puts a heavier load on it. So do that before inserting the 4th stick

My guess is ASUS failed to program the "Auto" voltage to raise this automatically. Keep in mind that until ASUS releases a BIOS upgrade addressing this, you will probably have to remember to remove a stick and do this again manually every time the CMOS is cleared.
 
Aug 30, 2019
6
0
10
0
well your x390 will need 4 same sticks (same timings) u cant run one set of timing on one channel, and 2nd one the other

tho its not impossible to do so
try first with increasing memory controller/ram voltage

anyway, please write part numbers for your ram
Both sets of ram have the following part number: F4-2400C15D-16GTZR
 
Aug 30, 2019
6
0
10
0
Yep, it's pretty normal to have to up the memory controller or RAM voltage when filling all slots, because that puts a heavier load on it. So do that before inserting the 4th stick

My guess is ASUS failed to program the "Auto" voltage to raise this automatically. Keep in mind that until ASUS releases a BIOS upgrade addressing this, you will probably have to remember to remove a stick and do this again manually every time the CMOS is cleared.
I have tried increasing the ram voltage with no success... I don't typically do things manually - i normally use auto overclocking tools for cpu ect so i dont realy know what values are safe for ram. It was running at 1.190 and i upped it to 1.400 which seems a little high? either way it still wouldn't work.

The specific part i have isn't listen on the Motherboards QVL but yet 3 of them work? Just not 4? which seems odd (F4-2400C15D-16GTZR )
 

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